© 2019 Department of Petroleum Resources. All rights reserved Department of Petroleum Resources (DPR) PROCEDURE GUIDE

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1.2.4 The design and installation of the lock valve shall be approved and supervised by the
Department of Petroleum Resources. After the installation of the lock valve has been found
satisfactory by the Director of Petroleum Resources, all the keys to the lock shall be kept in
the custody of the Department of Petroleum Resources Official – In – Charge of operations
at the facility.
1.3 CLASSES OF MEASUREMENTS.
1.3.1 CLASS A MEASUREMENT
The metering stations used for the delivery of petroleum to offshore customers and where
sales contracts are applicable. The DPR officer(s) shall monitor and supervise the systems
operations as applicable in the terminals for tax or royalty. The required overall
measurement uncertainty shall be less than 1% on a volume basis for gas or as specified in
the contract and approved by DPR.
1.3.2 CLASS B MEASUREMENT
The metering stations for the delivery of petroleum in commonly used pipeline systems and
where allocation procedures or joint operating contracts apply. This includes production
metering for MER allocation. The DPR shall be furnished on a weekly basis the daily
measurement record of the meter for accountability. The DPR officer(s) physical
involvement in the system operations shall be intermittent, at least fortnightly. The required
overall measurement uncertainty shall be less than 1.8% on a volume basis for gas or as
specified in the contract.
1.3.3 CLASS C MEASUREMENT
The metering stations for the delivery of fuel gas within the operator’s operating facility or
to third party facility. The uncertainty limit shall be ± 2 % of standard volume. The DPR
involvement is as in CLASS B.
1.4.4 CLASS D MEASUREMENT
The Metering station for flare and injection gas measurement. The uncertainty limit shall be
±5% of standard volume. If the flare gas releases are due to the operational upset,
blowdown, purging, or ESD operation the meter readings so recorded shall be forwarded
within 24hours to the DPR nearest office with a detailed report on the scenarios of the
releases. This report shall form the basis of zero charges on the flare gas releases while
charges shall be sustained if the flare releases are operational philosophy. The DPR
officer(s) involvement in the metering operations shall comply with CLASS B measurement
systems. The uncertainty is given in standard volume, but other units may be requested
(project specific) e.g. mass energy, etc.
Note: Any other uncertainty limit may be applicable for fiscal measurement systems if
validated by a cost-benefit analysis performed and accepted by the DPR.
1.5 UNCERTAINTY ANALYSIS
An uncertainty analysis shall be developed for gas metering systems within 95% confidence
level in accordance with recognized standards. The total gas metering system uncertainty
shall, for the operating flow range, be below +/- 1.0% (mass metering). If a deviation on any
of the equipment tolerances exists, it should be demonstrated that the metering system is
within the limits for total uncertainty given in this section.